Thank you, it certainly looks much better in person and I'm happy with the results.
When I said clean the teeth, don't worry too much, you don't have to strip the paint or anything. Just rub them down with some rubbing alcohol or something to remove any grime. If you have any stubborn blemishes, you could sand them with very fine polishing pads or something, normally I'd do this anyway but I'm keeping things simple here best I can so don't worry too much.
As for the black, I may have confused you. The gloss black I referred too is the undercoat for the chrome, alclad in particular requires such a base coat to work properly. So you would mask off everything except for the teeth which you wish to piant. For this you can use a combination of Tamiya masking tape, some masking liquids etc and paper for bigger areas. Then you want to paint the teeth completely black and allow them to dry before starting with the metallic paints. This stage depends on the paint you use though and may not be necessary, I'm just assuming you want the best finish possible and this is one of the best ways to achieve this. Some people are rebels and use white paint as a base, experiment and see what works best for you.
I wouldn't recommend brush painting unless you are much better at it than I, it is certainly a skill some people are just born with. I say this because with paints like this, brush strokes could easily kill the look. I would suggest you just get some spray cans, mask it all off as above and apply the gloss black, always be reserved and apply thin coats otherwise the paint will just pool and run, you can always add more if need be. Then find the metallic colour you need and apply it on top of the black, again be very sparing and expect to apply three or four coats, leaving suitable drying time between each. I can't recommend a particular brand as I don't use rattle cans myself, I'm sure somebody will know some.
The teeth are badly sculpted on the big chap as you've mentioned, they have no gaps and look like one piece. I tried adding black washes to my warrior, but it didn't work well imo and I decided the clean chrome look was the way to go. With the big chap however, you could scrape some gaps between the teeth with a sharp scalpel. I practiced this on mine and it worked okay. If you wish to paint some black on top, that is up to you, just thin it well. You could apply a coat of varnish to the teeth first so that you can just wash it all off if you decide you don't like the look.
You won't make it worse than the factory look, you can't
Best of luck.
Here's a video that shows how to apply metal coats, basic but helpful. You could even just use this paint if you like? Alclad it is not, but it is also cheaper and much easier to use.
. What an awesome result! It changes completely the bust! 
